The present invention relates to testing emergency notification circuits, and specifically to a system and method for testing the wiring impedance of emergency notification circuits using an end-of-line capacitor.
Emergency notification circuits provide power to a plurality of notification devices such as sirens and strobe lights. These devices are used to alert persons in the area of an emergency condition. Therefore, it is necessary to ensure the continuous functionality of these devices.
Each notification device requires a working voltage and current to operate. The wires that provide the voltage and current to the devices have an impedance themselves. If a condition occurs which causes the wiring impedance to change, such as a short circuit or open circuit condition, the notification devices may not receive the proper working voltage and current. It is therefore necessary to monitor the wiring impedance of the emergency notification circuit in order to ensure continuous operation of every notification device.
Previous circuits have utilized an end-of-line resistor in parallel with the notification devices in order to monitor for short circuit and open circuit conditions. To test the circuit, the voltage across the notification devices is reversed so as not to turn on the devices. The current through the resistor is monitored to determine if there is a short circuit condition or an open circuit condition. However, a condition causing the wiring impedance to rise but not fully cause an open circuit condition, such that some notification devices do not receive a working voltage and current, is not detectable by the end-of line resistor configuration.